Detecting Falsified Viagra Using Miniaturized Consumer Near-Infrared

The miniaturized Near-Infrared Spectroscopy (NIRS) enables convenient, non-destructive and real-time testing of medicines that are circulating on the field or throughout the supply chain. We have successfully been able to detect falsified Viagra using a new low-cost, consumer-type NIRS. In like manner, we have distinguished the original Viagra from its generic versions with the same dose. This is a promising way of ensuring medicines authenticity by looking at their chemical ‘fingerprints’. Portable screening technologies for medicine quality assurance on the field or throughout the supply chain are currently growing and complementing the current approach for combating the falsified products, i.e., safety features on the packaging and laboratory analysis of suspect samples. In total, 78 spectra of Sildenafil-based tablets were recorded and classified using the K-Nearest Neighbors algorithm that relies on the Euclidean distances between measured values. Accuracy of our model was assessed using crossvalidation and bootstrapping techniques. In result, the miniaturized NIRS correctly ordered all tablets according to their manufacturer and indicated the falsified tablets, which spectra not only differed in shape from the authentic versions, but also show high spread in chemo-physical characteristics, which suggest poor manufacturing practices of the falsified products.